Feynmp together with beamer

Question

How do you include a Feynman diagram in a beamer presentation?

\documentclass{beamer}
\usepackage{amsmath, amsthm, amssymb,latexsym}
\usepackage{slashed}
\usepackage{graphicx}
\usepackage{pgfplots}
\usepackage{bbm}
\usepackage{epstopdf} 
\usepackage{hyperref}
\usepackage{tikz}
\usepackage{tabularx}
\usetikzlibrary{calc,decorations.markings}
\usepackage{feynmp}
\mode<presentation> {
\usetheme{Warsaw}
    }
  \section{Theory}
\subsection{The diagram}
\frame
{
    \frametitle{the title etc}
    \begin{figure}
    \begin{fmffile}{Feynman1}
    \fmfframe(-20,-30)(-20,-100){
    \begin{fmfgraph*}(40,40)
        \fmfleft{i1,i2,i3}
        here is the feynmp code....\end{fmfgraph*}
        }
    \end{fmffile}
    \end{figure}
}

\end{document}

The Feynman diagram doesn't show up for me. What am I doing wrong, any suggestions?

Answer 1

This works:

\documentclass{beamer}
\usepackage{feynmp-auto}

\mode<presentation> {
  \usetheme{Warsaw}
}

\begin{document}

\section{Theory}
\subsection{The diagram}

\begin{frame}[fragile]
\frametitle{the title etc}

\begin{fmffile}{Feynman1}
\begin{fmfgraph*}(40,30)
  \fmfpen{thick}
  \fmfleft{i1,i2} \fmfright{o1,o2}
  \fmf{fermion}{i1,v1,o1} \fmf{fermion}{i2,v2,o2}
  \fmf{photon,label=$q$}{v1,v2} \fmfdot{v1,v2}
\end{fmfgraph*}
\end{fmffile}

\end{frame}

\end{document}

Compile twice.

Answer 2

I recently included a feynmp graph in a beamer presentation and it worked. I think I remember having had some trouble with this, but for me including

\DeclareGraphicsRule{*}{mps}{*}{} 

in the preamble did the trick. This is also the only obvious difference between our source files. With this you can just use feynmp as usual, where "usual" for me is: compile your code, run metapost on the produced files in a terminal, then recompile. If you already produced the files it might be enough to just recompile.